Thanks for writing to HCM
Normally consistency of semen is thick and colour is pearly white.
But consistency depends upon various things like, frequency of ejaculation, diet,genetics etc. Don't worry. Semen may normally become thinner if you ejaculate excessively.
For problems of abdomen you can go ultrasound
of abdomen as it will clear your doubt.
For stomach ulcer
you can take proton pump
inhibitors along with ulcer coating gel.